He expresses a strong artistic vocation since young, showing interest not just in cinema, but in literature too. At seventeen he kept a diary, Desarrollo de un proceso (Development of a process), where he records his may interests and concerns, many of them of a religious nature; he writes: 'I'm very sensitive to the good and beautiful. Sensitive to sensibility'. His readings and films he watched are very diverse and heterogeneous.

Living in Zaragoza as a university student, he write his text Händelequia, including photographs, newspaper ads, cartoon vignettes, philosophical and ideological themed discourses, etc... This text will serve as script for his first feature film, shot between 1967 and 1968, El lobby contra el cordero, filmed with continuous improvisations and ignoring any kind of technical orthodoxy: badly focused shots, careless lighting, questionable camera movements, etc. Ritual, the reflection on the film, millitant social attitudes (student protests, subversive proclamations) and mass pop culture (puppets, posters, department stores) are its contents.

His collaboration with the poet Eduardo Hervás gives birth to his next film, made in Valencia, Orfeo filmando en el campo de batalla (Orpheus filming in the battlefield) (1968-69), an attempt to combine the classical myth of Orpheus applied to the capitalist society wwith the theft of a film camera. Hervás and Maenza caused a very tense shooting dute to authorship disputes. The main argument will be film at the service of political militancy, describing a society in crisis in which one can only detach from it through the free and hedonist sexuality practiced in the private sphere.

His last film, Hortensia (1969), shot in Barcelona and produced by Pere Portabella, exists only as a workprint, without any chance of watching the final edit, but the available images -shots of great aesthetical impact in their composition- gives the impression that Maenza had left the previous technical mschiefs behind, showing greater expertise with the medium. Dramatization (masks, allusions to the 'Noh' theater), happenings and ceremonials are the focus of many sequences.

Maenza's cinema, his thinking about his practice, dealt primarily with the 'idea' and not so much about its realization leading him to be integrated among artistic movements such as conceptual art. His personal universe was akin to the contemporary avant-garde: situationism, body art, french structuralism, arte povera, etc...

After his painful stay in the compulsory military service (he was in charge of cleaning the stables of the barracks), the deaths of both his mother and his friend Eduardo Hervás (who commited suicide by coal gas posioning) his mental and phisical decline was unstoppable, leading him to be institutionalized with symptoms of schizophrenia, unable to gather the minimum stability required to continue working. Pere Portabella said of him: 'He was consumed by his own voracity, was against his time.' In late 1979 he was found seriously wounded near his home with signs of having been beaten and died a few days after. The circumstances of his death remain unclear, suggesting the possibility of suicide.

Besides his films, Maenza left behind numerous written texts, such as Aquiles inmóvil (short art film) and an untitled synopsis under the heading El mundo es un hospital en el que cada enfermo quiere cambiar de cama (The world is a hospital where every patient wants each other's bed). He also left many poems and an unfinished novel, Séptimo medio indisponible.